JOHN DE MOHUN, son and heir by 1st wife. He was a knight. He married Joan, 5th daughter of William (DE FERRERS), EARL OF DERBY, younger sister of his stepmother and coheir of their mother. He was living 29 July 1253, but died v.p., 1253-54, in Gascony. His heart was buried at Newenham Abbey, and his body at Bruton. His widow's marriage was granted to Piers de Chauvent, but bought of him for 200 marks by Sir Robert AGUILLON, whom she married in or before August 1256. She died before June 1269, and appears to have been dead in October 1267. [Complete Peerage IX:21, (transcribed by Dave Utzinger)]